Vacuum insulation panels (VIP) are panels that are poor thermal conductors and used where a temperature gradient needs to be maintained. These panels consist of a core that is a poor thermal insulator when placed in a low pressure environment (less than 100 microns), a getter (materials which adsorbs moisture and gas) and an outer envelope.
A vacuum insulated panel (VIP) is a form of thermal insulation made up of a nearly gas-tight enclosure surrounding a rigid core, from which the gas has been evacuated. Vacuum insulation panels are used to decrease the heat leakage from a structure or volume and therefore increase energy efficiency. Vacuum insulation panels are typically used inside refrigerator cabinets, freezers, vending machines, mobile refrigeration solutions, building construction, medical related fields, as well as in association with any products that require low energy loss due to heat transfer.
There have been changes to some of the materials that have been used in VIPs, particularly the “core material”, such as shown in U.S. Pat. Nos. 5,330,816; 7,517,576 and U.S. patent application No. 2012/00009376 A1. However, current processes of manufacturing VIPs have remained the same for some time and one such process is typically set forth in U.S. Pat. No. 5,364,577:
1. The core material, usually an inorganic “board” or panel, is manufactured and placed in a dry environment.
2. The panel is then heated and placed into a large chamber that is able to go to the desired pressures.
3. A getter is then placed next to the core material.
4. The getter and the core material are heat sealed in an envelope. The envelope is made of aluminum, a form of metalized plastic, or thick (>0.003 inches) stainless steel.
5. Sometimes manufacturers will place some helium in the envelope prior to sealing for quality control purposes once the process is done.
Commercially available VIPs are clad in an aluminum/plastic foil laminate, and since aluminum has high thermal conductivity, edge losses can significantly reduce the effective insulation value of these VIPs. Both aluminum clad and metalized plastic envelopes are extremely fragile, and the requirement of a superstructure to attach a VIP to a building increases the retrofitting costs and represents additional thermal edge losses. The current method of manufacturing VIPs limits the maximum size of the VIPs. Gas is evacuated in the entire chamber where the VIP is present, and then the plastic VIP envelope is hot sealed all around the perimeter.
During the manufacturing of VIPs, the getter/desiccant in the enclosure is exposed to the manufacturing ambient and can lose effectiveness. The hermetic seal of the enclosure is by a plastic to plastic weld and is more permeable than a metal to metal weld. The current VIP envelopes are easily punctured, thus quickly reducing the effective R value of the VIP. One other problem with small VIPs is that the edge thermal losses can easily exceed the area thermal losses. For a VIP encased in 0.3 mil aluminum foil the significant thermal short at the edges of the VIP greatly reduces the effective R value of the VIP.
It is an objective of the present invention to create inexpensive hermetically sealed, puncture resistant vacuum insulated panels of arbitrary size and shape with high R value and reduce the VIPs' thermal edge losses. One other objective of the present invention is to create and deliver a non-evaporable getter with high porosity to the enclosure of the VIPs. A further objective is to minimize water permeation and corrosion of the VIPs.